Safety device for electric lamps.



. G. W. EISBNMANN. SAFETY DEVICE ronf ELECTRIC LAMPS.

APPLICATION IIL I ID APR. 16, 1009.

Patented Apr. 19, 1910.

INVENTOR Carl illzlreamarzn WW A m mamas rs CARL WILLIAM EISENMANN, OF KANSAS CITY, MISSOURI.

SAFETY DEVICE FOR ELECTRIC LAMPS.

Specification of Letters Patent.

Patented Apr. 19, 1910.

Application filed April 16, 1909. Serial No. 490,271.

v To all whom it may concern:

Be it known that I, CARL W. EISENMANN, a sub ect of the German Emperor, and a resident of Kansas City, in the county of Jackson and State of Missouri, have invented a new and Improved Safety Device for Electric Lamps, of which the following is a full, clear, and exact description.

My invention .relates to safety devices for incandescent lamps using filaments orother incandescent members; my more particular purpose being to continue the activity of the Moreover, in filaments of the type now under discussion, it is usual either to connect together in series a considerable number of filaments or to mount the filament in a continuous length, and if any one of the series of filaments or any )art of the continuous filament is broken, t e entire lamp is rendered useless. \Vhat I seek to do,-therefore, in this invention, is to provide a lamp with a filament so mounted on supports that if the filament breaks between any two supports, that particular section is short-circuited so that the current may continue through the remainder of the filament. a

li/'hile the general purpose of my invention may be accomplished in a large number of ways, and it is impracticable to show them all, I disclose two particular constructions of lamp made in accordance with my invention.

Reference is to be had tothe accompanying drawings forming a part of this specification, in which similar characters of reference indicate corresponding parts in all the views. i

I Figure 1 is a perspective of an incandescent lamp having tantalum filaments and made in accordance with my invention; Fig, 2 is a view partly sectional and partly diagrammatic, showing'the arrangement of the filaments and of the wires of latent conductors used for short-circuiting them; Fig. 3 is a fragmentary perspective shouing a type of tantalum lamp a little different from that appearing in Fig. 1, the filaments in this instance being controllable by the electrostatic attraction of metallic leaves used for short-circuiting them under proper conditions; and Fig. 4 is a view somewhat similar to Fig. 2, but disclosing the construction appearin in Fig. 3.

At 5 is an exhausted g obe which is connected with a socket stem 6 whereby it is supported. Disposed within the globe and mounted upon the socket stem is a glass pedestal 7 and extending from the latter is a stem 8 provided with beads 9, 10, the stem 8 and the beads mentioned beim integral with each other and with the pet estal 7. 'The leading-in wires for the bulb. are shown at 11, 12 in Fig. 1 and are sealed into the glass of the pedestal 7. A number of metallic supporting pins 13, 14 are sealed into the head 9. For convenience in mounting, one of these pins 13 is integral with another 14, thus forming a member having substantially a V shape.

At 15, 15 are-shown a number of filaments of rare metal, such as tantalum or tungsten, each filament being connected with the supporting pins 13, 11. Sealed into the bead 10 are a number of supporting pins 16 disposed radially and engaging the middle portions of the respective filaments. At 17, 17 are a number of thin aluminum or magnesium wires slightly oxidized and provided with portions 18 which are wound around the pins 13, 1%, as indicated particularly 111 Fig 2. At 20, 21 are two supporting plus, and connected with the same is a filament 22, the middle of this filament being engaged by a supporting pin 23. The supporting pins 20, 21 are connected together by awire 2 1 having its ends 25, 26 wound around the supporting pins 20, 21. The supporting pins 20, 21, filament 22, supporting pins 23 and wire 21 correspond with the supporting pins 13, 1 1, the filament 15, the supporting pins 16 and the wire 17, with the exception that the filament 22 is broken and the associated parts just mentioned are therefore placed in a somewhat different relation.

The operation of the device shown in F lgs. 1 and 2 is as follows: Suppose that the filament is intact and that the current is turned filaments.

on, as in the case of any other incandescent lamp. The filament glows and produces the light desired. The current now passes in series through all of the various sections of The wires 17 being oxidized upon their peripheral surfaces as stated, are non-conductors. Suppose, now, that one of the filaments, say the one numbered 22, breaks as indicated in Fig. 2. The consequence is that the corresponding wire 24 is subjected to a greater potential strain than before. Hence, the delicate insulatiom formed by the slight coating of oxid upon its outer surface breaks down under theincreased electrical pressure, a slight fusion takes place between the Wire 24 and the pins upon which it is mounted,.and the wire 24 becomes, in effect, metallically connected to the supporting pins 20, 21. It now acts as a conductor and short-circuits the filament 22, allowing all of the other filaments 15 to glowas if nothing has happened.

As only a very short period usually a second or two, at the outside.is required in order for the current to cause the ends of the wire 24 to become connected with the supporting pins 20, 21, the lamp is not dim except for a moment.

In the form shown in Figs. 3 and 4, the

the leading-in wires at 29, 30, the latter being sealed into the pedestal. Two glass beads 31, 32, inte ral with the glass stem 33, are supported by the pedestal 28. Mounted upon the glass bead 31 are leaves 34, 35 ofexceedingly thin metal, preferably platinum foil, gold leaf, or some other metal made exceedingly light, thin and resilient. These leaves are provided with portions 36, 37 and are so arranged that the portion 36 of one leaf and the portion 37 of another leaf are exceedingly close together and are adapted to be drawn into contact with each other by electrostatic attraction when the difference in potential between them exceeds a certain predetermined limit. At 36, 37 is shown a pair of these leaves drawn into contact with each other. At 38, 39 are supporting pins and connected with the same 50 ar'efilaments 40, 40. Otherwise the construction is the same as in Figs. 1 and 2.

The operation of the device shown in Figs; 3 and 4 is as follows Thecurrent being turned on, the various filaments. 40, 40 are normally aglowl" As the current. is passing uniformly, there is a little electrostatic attraction between each leaf36 andthe ad'acent leaf 37, but this attraction is not su cient to draw the leaves just menti'oned into contact. Suppose, however, that a filamentfor instance, theone numbered figure. The difierence in potential between theleaves'36", 37" now becomes considerably greater than before, and approximates the globe appears at 27, the pedestal at 28 and pted to glow, means for sending a curdifference in potential of the line terminals.

The leaves 36*, 37 are thereby drawn directly into metallic contact, thereby shortcircuiting the filament 40 immediately restoring the conductivity of the lamp as a whole, the filament 40 being caused to glow, so that there is comparatively little interruption brought about by the rupture of a filament. s V

I do not limit myself to any particular materials to be used for the purposes above stated. Thisis particularly the case with. reference to the materials employed as fila- I ments and the substances used for the conducting members 17, 24, and the materials used in the formation of the leaves 36, 37 36, 37". Neither do I limit the disclosedv construction to lampls designed for multiple connection, since t is construction is admirably suited for lamps designed for series connection and difi'ering from known devices similar in principle in being less complicated and less expensive, and located inside the inclosing bulb of the lamp."

Having thus described my invention, I claim as new and desire to secure by Letters Patent:

1.- In a lamp, the combination of supporting pins, a filament mounted thereupon and rent through one of sa d supportln pins and through said filament to the ot er of said supporting pins, and a conducting wire slightly insulated and wound partially upon said supporting pins, so as to normally insu late'the same and yet to establish electrical communication between said supporting pins under proper changes of electrical con- .ditions in said supporting pins.

2. In a lamp, the combination of support ing members, .a filament supported by said supporting members,.and a conducting wire slightly oxidized and adapted to be fused thereto when the current through said wire is increased by the breaking' of said filao ment.

. 3. In a lamp, the combination of support-. mg members, a filament mounted thereupon and adapted to low, and a conducting member extending rom one of said supporting members to the other, said conducting memher being slightly insulated upon its outer surface for the purpose of temporarily serving as an insulator but adapted to increase in conductivity when subjected to an excessive difference in potential.

' 4. In 'a'lamp, the combination of supporting members, a filament connected therewith and adapted to glow,.and a'single wire extending from one of said supporting members to the, other, said wire being slightly 40, Fig.' 4-breaks, as indicated in this tween said insulating members under proper changes of electrical conditions in said supporting members.

5. In a lamp, the combination of supporting members, a filament mounted thereupon and adapted to glow, means for sending a current through one of said supporting members and through said filament to the other supporting member, and a conducting wire, provided with a film of oxid, which engages said supporting members and normally insulates the same.

6. In a. lamp, the combination of supporting members, a filament extending from one of said supporting members to another, and mechanism connected electrically with said a supporting members and controllable directly by excessive differences in potential 01 short-circuiting said supporting memers.

7. In a lamp, the combination of supporting pins insulated from each other, a filament extending from one of said supporting pins to another, said filament being adapted to glow, and means controllable by differences in potential of said pins forshortcircuiting the latter.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

CARL WILLIAM EISENMANN.

WVitnesses:

W. T. BROCKMAN, RAY P. STAUFFER. 

